1. Technical Field
The present invention relates to a biochip, a reactor, and a reaction method.
2. Related Art
Currently, with the recent reveal of the presence of genes concerned with various diseases, medical treatment utilizing genes such as genetic diagnosis and genetic treatment has been attracting attention. Moreover, a number of techniques utilizing genes have been developed in the fields of agriculture and stock-breeding for judgment and improvement of species. Thus, technologies associated with genes have been expanding in various fields these days. In utilizing genes, nucleic acid amplification technology is widely used at present. For example, PCR (polymerase chain reaction) is a typical known method as the nucleic acid amplification technology. Today, PCR is an essential technique for clarifying information on living substances.
According to tests using PCR, a method which causes reaction by using a sample reaction container called a tube or a chip (biochip) is generally employed. However, several problems arise from the method generally used, including a large quantity of necessary reagents or the like, complication of a device used for producing a necessary thermal cycle, and a long period for reaction. Therefore, such a biochip or a reactor which uses only a small amount of reagents or samples and performs PCR with high accuracy in a short period has been demanded.
For providing this type of biochip or reactor, JP-A-2009-136250 proposes a biochip and a reactor which produce a thermal cycle for reaction by reciprocating a liquid sample (liquid including a sample) contained as droplets in a tube filled with liquid (such as mineral oil) not miscible with the liquid sample and having a smaller specific gravity than that of the liquid sample.
According to this technology, however, a step for maintaining the liquid sample at a predetermined temperature for a predetermined period is required in many cases prior to start of PCR.
For example, in case of PCR performing hot start by using Taq polymerase, a maintenance period at 95° C. for about 5 minutes is required. For a test of an RNA virus such as an influenza virus, PCR is generally executed after reverse transcription from RNA to cDNA. In this case, a maintenance period at 45° C. for about 30 minutes is required, for example.
For providing the necessary maintenance temperature and maintenance period as above for the reactor disclosed in JP-A-2009-136250, a method which includes a step of maintaining the liquid sample at the predetermined temperature for the predetermined period by using another device, or a method which maintains the liquid sample at the predetermined temperature for the predetermined period while stopping the rotation of a holder holding a biochip is adopted, for example.
According to the former method, however, the labor of detaching the biochip from one device and attaching the biochip to the other device is required. In case of the latter method, the advantage that a plurality of biochips prepared at different times can be successively processed is not provided.